The present invention relates to polyketone copolymer compositions comprising certain additives. The relevant copolymers are characterized by having an alternating structure [A-CO].sub.n in which a unit A is positioned left and right in between carbon monoxide units. A is a unit derived from an olefinically unsaturated compound. The term "copolymer" includes terpolymers in which different units A are present. As an example of suitable terpolymers reference is made to a copolymer of ethene, carbon monoxide and propene or butene. Other suitable monomers yielding a unit A are e.g. styrene, butene, octene and acrylate esters.
The relevant alternating copolymers and their methods of preparation are known per se, U.S. Pat. No. 3,694,412, and European Patent Applications 121,965 and 181,014. While these copolymers have attractive physical and mechanical properties such as yield stress, tensile strength, impact strength and flexural modulus, their processing performance leaves room for improvement.
Extrusion of copolymer with an intrinsic viscosity, or limited viscosity number (LVN) above 2.0 dl/g (measured at 60.degree. C. in m-cresol) is adversely affected by poor melt flow. Since copolymers with a high LVN have better physical properties, and would be very successful as fiber material and as engineering thermoplastics, this problem needs to be solved. Especially in fiber applications, melt-extrusion is a critical step, even for copolymers with a low LVN.
It has been found now that the melt flow properties of the above-mentioned polyketones can be improved by incorporating certain additives selected from acid amides and aluminium-oxygen compounds. The better melt flow properties allow processing, such as extrusion, to be carried out more easily, with less intrinsic friction, i.e. less local heating and degradation of the polymer. It has been found too that certain additives, when used in combination, show synergy, and that other additives, which are known per se as antioxidants for other polymers, act as melt flow improvers as well, when used in combination with the first mentioned amides or aluminium-oxygen compounds.